Suggestions for LetLtxMacro

The following packages have something in common with the package LetLtxMacro. The packages are ordered in decreasing similarity.

Package xfp: Interface to the LaTeX3 floating point unit
Package xparse: A generic document command parser
Package inlinedef: Inline expansions within definitions
Package xtemplate: A high-level interface for declaring document commands
Package namedef: TeX definitions with named parameters
Package styledcmd: Handling multiple versions of user-defined macros
Package ccool: A key-value document command parser
Package ltxnew: A simple means of creating commands
Package xoptarg: Expandable macros that take an optional argument
Package xnewcommand: Define \global and \protected commands with \newcommand
Package optparams: Macros with multiple optional parameters
Package cdcmd: Expandable conditional commands for LaTeX
Package lambdax: Use Lambda expression within LaTeX
Package mathcommand: \newcommand-like commands for defining math macros
Package cssyntax: Readable, self-documenting command names for LaTeX package authors
Package lparse: Parse macro arguments with Lua using xparse-like specification
Package defstring: Define macros as verbatim macros
Package getoptk: Define macros with sophisticated options
Package forloop: Iteration in LaTeX
Package dvisvgm-def: Colour and Graphics support for dvisvgm
Package dvipdfmx-def: Configuration file for dvipdfmx graphics
Package pdftex-def: Colour and Graphics support for pdfTeX
Package graphics-def: Colour and graphics option files
Package serbian-def-cyr: Serbian cyrillic localization
Package eolgrab: Catch arguments delimited by end of line
Package savesym: Redefine symbols where names conflict
Package flags: Setting and clearing of flags in bit fields
Package twoopt: Definitions with two optional arguments
Package authoraftertitle: Make author, etc., available after \maketitle
Package aliascnt: Alias counters
Package catchfile: Catch an external file into a macro